Color photographic light-sensitive element containing magenta coupler and alkyl phosphate solvent

ABSTRACT

WHEREIN R1 AND R2 EACH IS AN ALKYL GROUP AND WHEREIN R3 REPRESENTS A MEMBER SELECTED FROM A GROUP CONSISTING OF AN ALKYL GROUP AND AN ARYL GROUP, AND WHEREIN THE TOTAL NUMBER OF THE CARBON ATOMS IN R1, R2 AND R3 RANGES FROM 14 TO 40 CARBONS ATOMS, IS DISCLOSED.   R2-O-P(=O)(-O-R1)-O-R3   A LIGHT-SENSITIVE MATERIAL COMPRISING AT LEAST A LAYER OF A SILVER HALIDE EMULSION CONTAINING (1) A NON-DIFFUSING 5-PYRAZOLONE COUPLER HAVING AT LEAST A HYDROPHOBIC BALLASTING GROUP CONTAINING FROM 9 TO 30 CARBON ATOMS AND (2) A COUPLER SOLVENT HAVING THE FORMULA

y 11, 1972 EIICHI mum ETAL 3,676,137

COLOR PHOTOGRAPHIC LIGHT-SENSITIVE ELEMENT CONTAINING MAGENTA COUPLER AND ALKYL PHOSPHATE SOLVENT Filed Aug. 27, 1970 HGI ABSORBANCE ABSORBANCE FIG. 3

z; [mamas EHCHI mzux:

YASUSHI orsm MASAO SAWAHARA 0 I I R rd 4 500 600 700 lm- 2;. :24 1x WAVE LENGTH (MILLIMICRON) 7e ATTORNEYS United States Patent Int. Cl. Goscmo, 1/40 US. Cl. 96-565 20 Claims ABSTRACT OF THE DISCLOSURE A light-sensitive material comprising at least a layer of a silver halide emulsion containing (1) a non-diffusing S-pyrazolone coupler having at least a hydrophobic ballasting group containing from 9 to 30 carbon atoms and (2) a coupler solvent having the formula wherein R and R each is an alkyl group and wherein R represents a member selected from a group consisting of an alkyl group and an aryl group, and wherein the total number of the carbon atoms in R R and R ranges from 14 to 40 carbon atoms, is disclosed.

BACKGROUND OF THE INVENTION (1) Field of the invention The present invention relates to a color photographic light-sensitive element containing couplers. More particularly, the present invention relates to a color photographic light-sensitive element containing a S-pyrazolonetype magenta forming coupler and an alkyl phosphate for dissolving the cpupler. l

(2) Description of the prior art For the formation of color photographic images by subtractive color processes there have beengenerally used an N,N-di-substituted p-phenylenediamine compound as a developing agent for developing the silver halide emulsion and couplers that form cyan, magenta and yellow dyes by coupling with the oxidation product of the developing agent formed simultaneously at development.

In color photography by the subtractive color process a magenta color image has light absorption mainly in the wave length region of from about 4 80 to about 600 mp. and the spectral absorption characteristics required for the magenta coupler in the wave length region depend upon the purposes of the color photograph. Particularly, for direct observations of the colors by the naked eye, it is necessary to keep low the absorption of the magenta color image in the red region at the longer wave length side.

In a system in which each of the couplers is preliminarily incorporated in each of the silver halide emulsions having a ditferent spectral sensitivity during the course of producing color photographic light-sensitive elements, it is necessary that the couplers be provided with a diffusion resisting property in order to prevent the couplers from migrating into the other emulsions and from deteriorating the quality of the color reproduction by mixing with each other. It is well known that for these purposes a hydrophobic radical having more than 8 carbon atoms is introduced to the coupler molecule.

Various methods have hitherto been proposed for incorporating such diffusion resisting couplers into photographic emulsion layers. Among them, however, the following two methods are particularly important from a practical standpoint. These methods are an aqueous solution system and an oil solution system. In the aqueous solution system the coupler has a water-solubilizing radical and is added to a photographic emulsion mainly as an alkaline aqueous solution. On the other hand, in the oil solution system the coupler is dissolved in an organic solvent, the solution thus obtained is dispersed by emulsification in an aqueous medium as fine colloidal particles, and then the dispersion is added to a photographic emulsion as described in the specification of, for example, US. Pat. No. 2,322,027.

A magenta-forming coupler incorporated in a photographic emulsion layer by the oil solution system or a system similar to the oil solution system generally provides a color image having excellent spectral absorption characteristics and high humidity resistance in comparison with a magenta-forming coupler incorporated by the aqueous solution system. In order to intensify these advantages and to facilitate further the production of color photographic light-sensitive elements, it is necessary that the coupler used in the oil solution system and the dye formed from the coupler be highly soluble in an organic solvent for dispersing the coupler and be less crystallizable.

For dispersing the coupler using the oil solution system a high boiling organic solvent is used. Besides dissolving the coupler during the dispersion of the coupler, the solvent contributes to the prevention of crystallization of the couplers, with crystallization causing a loss of the coupling reactivity of the coupler. The solvents dissolve the dye formed by the coupling of the coupler at development, whereby deterioration of the spectral absorption characteristics by the excessive crystallization of the dye is prevented.

As magenta-forming couplers 5-pyrazolone derivatives in general are widely used. However, since the S-pyrazolone derivatives are generally weakly soluble in many high boiling organic solvents conventionally used for dis persing couplers, such as the fatty acid esters, the aromatic carboxylic acid esters, the phosphoric acid aryl esters, and the phenol ethers, use of the pyrazolone derivatives results in difiiculties in that a large amount of solvent is required for emulsifying dispersion. In addition, the couplers tend to cause excessive crystallization during or after the production of the light-sensitive elements. Also, where a high boiling organic solvent is employed, the spectral absorption characteristics of the dye image formed have the disadvantages in that the whole absorption band of the dye image shifts to extremely longer wave lengths in comparison with that of the solution in said solvent and also the width of absorption region band increases giving rise to an adverse influence on the color reproduction of the color photograph.

On the other hand, an attempt toward increasing the dissolving power of the solvent to the coupler by increasing the polarity of the solvent results in the disadvantages that the absorption of the dye shifts to a longer wave length increasing the red absorption and also the hydrophylic property of the solvent is increased. Also, pyrazolone derivatives are generally sensitive to various kinds of chemical reagents and hence organic solvents such as ketones cannot be used as their solvent. In other words, the selection of the solvent is limited to a narrow range in this case.

Furthermore, when some organic solvents are used, a magenta coupler cannot show sufiiciently high coupling reaction on development. This is believed to be caused by the organic solvent hindering the reaction of the magenta coupler with the oxidation product of a color developing agent.

The inventors have discovered that a series of compounds show excellent dissolving power for the S-pyrazolone derivatives and the azomethine dyes formed therefrom, giving spectral absorption characteristics preferable for color reproduction in the magenta color image.

One object of this invention is to provide a solvent having a high dissolving power for s-pyrazolone derivatives and the azomethine dyes derived therefrom.

Another object of this invention is to provide a color photographic light-sensitive element forming a magenta color image having less absorption for red light on color development.

Another object of this invention is to provide a color photographic light-sensitive element which can be produced without causing excessive crystallization of the coupler during production and which can be stably stored after production.

SUMMARY OF THE INVENTION The above objects are accomplished by dispersing by emulsification of a pyrazolone coupler in a photographic emulsion by using a phosphoric acid ester as a novel solvent for the coupler.

DESCRIPTION OF THE INVENTION The solvent for the coupler used profitably for incorporating the S-pyrazolone-type coupler in a photographic emulsion is represented by a phosphoric acid ester having the following Formula I O--Rr R -OP=O wherein R and R each represents an alkyl group; R represents an alkyl group or an aryl group, nd the sum of the carbon atoms included in the three residual groups R R and R is in the range of from 14 to 40.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS FIG. 1 is a graphical representation showing the spectral absorption curve obtained with one embodiment of this invention (Curve 1) in comparison with the use of conventional coupler solvents (Curves l1 and III).

FIG. 2 is a graphical representation showing the spectral absorption curve obtained with a second embodiment of this invention (Curve IV) in comparison with the use of conventional coupler solvents (Curve V).

FIG. 3 is a graphical representation of another embodiment of this invention (Curve VI) in comparison with the use of no coupler solvent (Curve VII).

DETAILED DESCRIPTION OF THE INVENTION The solvent for the coupler used profitably for incorporating the 5-pyrazolone-type coupler in a photographic emulsion is represented by a phosphoric acid ester having the following Formula I Rr-OF=O a wherein R and R each represents an alkyl group; R represents an alkyl group or an aryl group, and the sum of the carbon "atoms included in the three residual groups R R and R is in the range of from 14 to 40. If the sum of the carbon atoms is less than 14, the phosphoric acid ester represented by the general Formula I is soluble in aqueous media and hence will be dissolved in the processing bath during the developing process. Accordingly, there remains no solvent for the dye formed by coupling of the coupler in the photographic emulsion layer of the light-sensitive film after processing and then the dye is liable to crystallize. This results in the excellent spectral absorption characteristics obtained by the present invention not being obtained. Further-more, if the number of carbon atoms is less than 14, the phosphoric acid ester shown by the general Formula I may cause dilficulties in that the ester difiuses into other emulsion layers and finally reaches the plastic support softening excessively the plastic support. Additionally, if a paper support is employed the reflection power of the paper support is reduced. On the other hand, if the total number of carbon atoms is greater than 40, the action of the phosphoric acid ester as a solvent for the coupler and the dye formed from the coupler is reduced, whereby the advantages of this invention cannot be obtained.

Suitable examples of solvents represented by the general Formula I used in this invention are shown below:

Solvent for the coupler:

'(a) Diethyldodecyl phosphate (b) Dibutylhexyl phosphate (c) Tri-n-amyl phosphate (d) Di-n butyl-(2-ethylhexyl) phosphate (e) Di-n-hexyl-n-amyl phosphate (f) Tri-n-hexyl phosphate (g) Diethyl-(2,4-di-tert=butylphenyl) phosphate (h) Di-n-hexyl phenyl phosphate (j) Di-(Z-ethylhexyl)-n-buty1 phosphate (k) Di-n-heptyl-n-hexyl phosphate (1) Tri-n-heptyl phosphate (m) Tri (2-ethylhexyl) phosphate (11) Di-n-butyl-(S-n-pentadecylphenyl) phosphate (0) Di-n-hexyl-(4-n-nonylphenyl) phosphate (p) Tridecyl phosphate, and (q) Tridodecyl phosphate.

The magenta couplers used in this invention can be selected from a wide range of magenta couplers. Among them, the S-pyrazolone compounds that find particularly excellent results when used together with the phosphoric acid esters having the above-described structural Formula I belong to the groups of the' compounds represented by the following general Formulae H and III:

wherein R represents an aryl group or a substituted aryl group in which the preferred substituents for the aryl group are an alkyl group, an aryl group, an alkoxyl group, an aryloxy group, an alkylthio group, an arylthio group, a halogen atom, a trifluoromethyl group, a cyano group, an acyl group, a sulfonyl group, an acylamino group, a sulfonamino group, a ureido group, an amino group, a carboxyl group, an alkoxycarbonyl group, and a carbamyl group and in particular phenyl groups substituted by these substituents are preferred as the R group; wherein R represents an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an aryl group, a substituted aryl group, an amino group, a substituted amino group, an acylamino group, a substituted ureido group, a sulfonamido group, and an alkoxyl group; and wherein X represents a residual group capable of being isolated by the oxidation product of an aromatic primary amino color developing agent, such as a hydrogen atom, a halogen atom, a cyano group, an arylthio group, an aryloxy group, an arylazo group, a heteroazo group, an acyloxy group; wherein at least one of said R and R includes a hydrophobic residual group (i.e., a ballastin-g group) having from 9 to 30 carbon atoms. By the presence of the hydrophobic residual group the affinity between individual coupler molecules and between the coupler molecules and the solvent molecules is increased, whereby the coupler remains in or near fine particles of the solvent and then the coupler can be intimately contacted with the solvent. The dye derived from such a coupler has an afiinity to the solvent. The hydrophobic residual group is included in the R or the R group and is bonded to the coupler residual group directly or through a divalent organic residual group having an amide-bond, an ether bond, an ester bond, a urea bond, or a sulfonamido bond.

The hydrophobic residual group advantageous to the present invention is selected from a straight chain or branched alkyl group, an alkenyl group, an alkoxyalkyl group, an alkoxyaryl group, an aryl group, an allyloxyalkyl group, aryloxyaryl group, and acylaminoalkyl group. Specific examples of them are shown below:

| O C H2- (vii) SEC-CsHu- O 0 Hz- 81 511 1-560 (viii) (EH5 teliJ-C4Hr o c H 4H9-t9lt 0 4i isHa 1- N- 0 Hz C H 2- Specific examples of the S-pyrazolone compounds used preferably in the present invention are as follows:

Coupler M.P., C.

A CI 82-84 /N= CC1TH35 Cl N\ C-CH 01 \l B N=C-C|7H3s 121 C-CH, I!

/N=C-O CiaHu @a C-CH D Cl 104-105 /N=C 0 CiaHa1 01 N\ l I C-CH; Cl l /N=(|3NHNHC 0 oHl0--o,m1 (t) QR 1;

I H2 6 u( 01 ll F "2.-.? C H 1(t) 172 /N=GNH- NHCO(|JHO C n(t) Cl- N\ (32H,

C-CH: l l I G C O 0 H23 Coupler M.P., C.

N=CNHCONH 01H, on,- N I NHCOCHO CsHMt) 1 (3- Ha I c ina U Cl C NHCOQ 150-153 NHCOCHaO- Cs M C-CH or g l N=N 0 CH; 03 11) /N=CNHCONH 0,Hn(t) on o- N \c L Nrrcoomo c i a T0,;HMt)--OCH,CONHQ CHCH| opium ONH(3-CH- N\ ':=o

C Hiflt) CONHC--CH- In producing the color photographic light-sensitive elecoupler can be dispersed alone by itself as a melt thereof ment of the present invention, the S-pyrazolone coupler described above is dispersed in a photographic emulsion by an oil solution system. That is to say, the 5-pyrazolone compound is dissolved in the phosphoric acid ester and then the resulting solution is dispersed in a photographic aqueous medium. In this case, it is profitable to use a surface active agent described in the specification of Japanese Pat. No. 428,191 and Japanese patent application No. 60,130/ 68. For accelerating the dissolution of the coupler in the solvent for the coupler, it is advantageous to use together an organic solvent which is partially dissolved in water and has a comparatively low boiling point. The practical examples of such subsidiary solvents are sec-butyl alcohol, hexanol, cyclohexanol, ethyl acetate, butyl acetate, ethyl propionate, tetrahydrofuran and the like.

For producing the color photographic light-sensitive element of this invention it is not always necessary to disperse the 5-pyrazolone coupler after mixing with the phosphate represented by the general Formula I. The

or as a solution in an auxiliary solvent having a comparatively low boiling point and the phosphate dispersed separately. They can be mixed with each other. Alternatively, the 5-pyrazolone coupler can be incorporated in a photographic emulsion using a method in which the coupler is dissolved in an alkaline aqueous solution, the solution thus obtained is added to a photographic emulsion in the presence of a dispersion of the phosphoric acid ester, and then the emulsion is neutralized. In this case, to aid the resolution of the coupler in an aqueous medium, it is advantageous to use an organic solvent miscible with water, such as methanol, ethanol, dioxane, dimethyl formamide, and dimethyl sulfoxide.

For the method in which the coupler is added to the photographic emulsion as an alkaline aqueous solution thereof, a S-pyrazolone coupler having one carboxyl group is particularly useful. The carboxyl group is present mainly in the form of the free acid and shows a good affinity to the solvent except when the coupler is added to the emul- 11 sion as an alkaline aqueous solution. Thus, this kind of coupler and the dye derived therefrom shows afiinity for the coupler solvent represented by the general Formula I, and hence by the combination of the coupler and the coupler solvent, the above-described advantages of this invention, such as the good spectral absorption character- 12 and 12 of this invention and the numerical values in the examples.

These solvents used in this invention have a very high solvent action to the S-pyrazolone couplers and as a result the necessary amount of the solvent used for incorporation in a photographic emulsion can be reduced in comparison with the amount of a conventional solvent. By reducing the amount of solvent, it is possible to reduce the thickness of the emulsion layer and prevent excessive plasticization of the emulsion layer. Furthermore, since the solvent of this invention has a high solvent action to the coupler, excessive crystallization of the dispersed coupler during the manufacture of lightsensitive elements as well as in an emulsion layer containing it can be prevented and hence the color photographic light-sensitive element of this invention can be provided Coupler M.P., C.

(I; C-CH:

O OH. [I 0 Z N=F-NHC o CHCHCmHss -N crno OOH CCH2 ll 0 I n l "I A N=C-NHCO- \C H NHCO CH'CH=CHC1\H33 =0 11 omcoorr O N=CNH C O C1 N NHC O CH CH=CHC1| 3: 0-011: 01 II CHzCO OH N=CNH C O NHCOOH-CHCuHas C=CH1 C1 (III) CH: C O O H The proportion of the phosphate mentioned above to the S-pyrazolone coupler depends on the type of the light-sensitive element and the structure of the coupler but preferably ranges from 0.1 part by weight to 4.0 parts by weight to each part by weight of the S-pyrazolone coupler.

The practical advantages obtained by employing the novel coupler solvent used in this invention are as follows:

The S-pyrazolone-type coupler added to a photographic emulsion as an emulsified dispersion thereof together with the coupler solvent represented by the general Formula I on color development gives a magenta dye image having less absorption of red light having a wave length longer than 600 millimicrons. Consequently, the color photographic light-sensitive element of this invention can reproduce a clear red color. This is illustrated by the spectral absorption curves obtained in Examples 1, 2,

in a high production yield and stability. Still further, the comparatively low viscosity of the solvent facilitates dispersion of the coupler in an aqueous medium.

The solvent for the coupler represented by the general Formula I has a refractive index of about 1.44 and when the 5-pyrazolone compound is dissolved in the solvent, the refractive index of the solution reaches about 1.54 which is the refractive index of air-dried gelatin. Therefore, the gelatin layer containing the solvent and the 5- pyrazolone compound or the azomethine dye therefrom is less turbid and is clear. 0n the other hand, triaryl phosphate-type coupler solvent known hitherto, for example, a tri-o-cresyl phosphate, has a refractive index of about and when the coupler is added to the solvent, the refractive index of the solution is increased to about 16 and hence the emulsion layer after processing is a little turbid, this reducing the clearness of the color photograph.

Moreover, the coupler solvent represented by the general Formula I is less hydrolizable, whereas a conventionally known triaryl phosphate coupler solvent is readily hydrolyzed, this being one of the causes reducing the fastness of the color image formed.

The physical properties of the coupler solvent used in this invention are shown in the following table together with those of conventionally known solvents for couplers.

These experimental results show that solvents (c) and (f) of this invention have higher solvent action to the 5- pyrazolone coupler and to the dye derived therefrom than conventional coupler solvents, tri-o-cresyl phosphate (TCP) and di-n-butyl phosphate (DB-P).

Suitable examples of the N,N-di-substituted-o-phenylene diamine derivatives used for developing the color photographic light-sensitive element of this invention are as follows: N,N-dimethyl-p-phenylenediamine, N,N-di- TABLE 1 [Properties of aliphatic phosphorate-type solvent for coupler] No. Compound Boiling point (A) (B) (C) (a) Diethyl decyl phosphate 160 CJmm 1.432 0.930 0,05 Tri-n-amyl hosphate 158 to 163 0J6 mm 1.428 0.943 0.03 (d)- Dl-n-butyl-g-ethylhexyl) phosphate-- 156 C./mm 1. 430 0. 941 0.03 (i)- Trl-n-henyl phosphate 187 to 188 C-l2 mm 1. 433 0. 27 0. 03 Di-n-hexyl phen lester 178 to 182 C-/mm.- 1. 469 1. 003 0. 03 Di-(2-ethylhex.yl -n-hepty1phosp ate 177 C./mm 1.437 0. 919 0.03 Tri-n-hegtyl phosphate 172 .00 5 mm 1. 433 0.919 0. 03 (m) Trl-(2-et ylhexyl) phosphate 220 0J5 mm; 203 C./3.5 mm. 1. 441 0.913 0.03

Comparison compounds Di'n-butyl phosphate (DB P). 227 to 235 C./37 mm. 1 042 0, 03 Tri-o-eresyl phosphate (TCP) 265 to 285 C./ mm- 1, 166 0, 03 'Iri-n-butyl phosphate (TBP)-. 177 to 178 C./27 mm- 1, 423 o, 973 0, 0

NorE.-(A)=Refractive index at C. (no); (B)=Specifie gravity at 25 0.; (C)=Soluhil1ty in water at 25 C. (weight percent).

The results shown in the above table demonstrate that 25 ethyl-p-phenylenediamine, N-ethyl-N-(fi-hydroxyethyl)-pthe phosphoate-type coupler solvent shown by the general Formula I has a very low volatility and a sufi'lciently low water solubility and also when the coupler is dissolved in the solvent, the refractive index of the solvent approaches that of dried gelatin, this shows that the solvent is suitable for producing color photographic lightsensitive elements.

The experimental evidence showing that the novel coupler solvent useful for this invention has a high solvent action to the 5-pyrazolone-type magenta couplers and the azomethine dyes derived therefrom, will be illustrated below.

The S-pyrazolone coupler shown above by the structural formula K was dissolved in 4 types of coupler solvents at 25 C. to saturation. For this purpose, an excess amount of the coupler was added thereto and with frequent stirring, the mixture was allowed to stand for about 1 month. Then, the content of the coupler in the saturated solution was measured, the results are shown in Table 2.

Further, the azomethine dye having the following structure derived from the '5-pyrazolone coupler K was also dissolved in the 4-types of the solvent for coupler to saturation and the content of the dye in the saturated solution was measured, the results are also shown in Table 2.

Azomethine Dye:

(t) mm-Q-oomoonn phenylenediamine, 4 amino-3-methyl-N,N-diethylaniline, 4-amino-3-methyl N-ethyl-N-(B-hydroxyethyD-aniline, 4- amino 3 methyl N ethyl-N!(p-methanesulfonamidoethyl)aniline, and their salts. Among them developing agents substituted by an alkyl group, a substituted alkyl group or an alkoxyl group at one ortho position to the primary amino group are particularly useful. Although these ortho-substituted developing agents have a high dyeforming faculty as well as excellent advantages of giving a fast color image to light, heat, and humidity, they are still deficient at the point of bright red reproduction since the absorption of the color image obtained is at the longer wave length side.

Conversely, the use of the solvent for the coupler represented by the general Formula I compensates for the shift of the absorption of the color image to longer wave lengths and facilitates the use of ortho-substituted developing agents. That is to say, by the combination of both components, a color image having a clear red reproduction, a high color density, and a high fastness can be obtained. This is one of the advantages obtained by this invention.

The invention can be applied to various types of color photographic light-sensitive elements and can give color images having good properties. Examples are color printing papers, color photographic positive films, color photographic negative films, and color photographic reversal films.

Also, the invention can be applied to the so-called multilayer type color photographic light-sensitive element in which multiple emulsion layers, each containing a silver halide emulsion with a different spectral sensitivity and a corresponding diffusion-resisting coupler, are applied to a support and also to a mixed grain-type color photographic light-sensitive element as well as other types of light-sensitive elements.

The phosphate represented by the general Formula I to be used in this invention can be prepared by the reaction of phosphoryl tri-chloride and an alcohol or a phenol. Also, by utilizing the difference in the step-wise reactivity of the chlorine atoms of sulphoryl trichloride, a mixed ester can be produced easily. The alkyl group rep resented by R R and R of the general Formula I is preferably a primary alkyl group from a standpoint of the yield in producing the ester. Examples of producing the esters are illustrated by the following:

SYNTHESIS 1 Tri-n-hexyl phosphate The sythesis of the compound was carried out according to the method of producing tri-n-butyl phosphate described in Organic Synthesis Coll., vol. 11, page 109 using n-hexanol instead of n-butanol.

500 g. (4.9 mols) of water-free n-hexanol, 427 g. (5.4 mols) of water-free pyridine, and 650 ml. of water-free benzene were placed in a 3 liter three-necked flask equipped with an air-tight agitator, a dropping funnel, a thermometer, and a reflux condenser. The mixture was cooled to 5 C. while stirring and then 251 g. (164 mols) of phosphorus oxychloride was added dropwise to the mixture at temperatures lower than C. Thereafter, the reaction mixture was gradually heated and refluxed for 2 hours. Then, after lowering the temperature of the mixture to room temperature, 800 ml. of water was added to dis solve the pyridine hydrochloride and the benzene layer was separated, washed with water sufliciently, and dried using sodium sulfate. By distilling away the benzene under reduced pressure, 260 g. of the above-mentioned compound having a boiling point of 187-188 C/2 mm. Hg was obtained.

SYNTHESIS 2 Di-n-octyl-n-butyl phosphate 130 g. 2 mols) of water-free n-octanol, 174 g. (2.2 mols) of water-free pyridine, and 300 ml. of water-free benzene were placed in a 2 liter three-necked flask equipped with an air-tight agitator, a dropping funnel, a thermometer, and a reflux condenser. While stirring, the mixture was cooled to 5 C. and 191 g. (1 mol) of dichloro-n-butyl phosphate [produced by the method described in Journal of Chemical Society, 1466 (1940)] 'Was added dropwise at temperatures lower than 10 C. Thereafter, the reaction mixture was allowed to stand for 1 hour at the same temperature and for 2 hours at room temperature, and then refluxed for 2 hours. After the temperature of the mixture was reduced to room temperature, 300 ml. of water was added to the mixture to dissolve the pyridine hydrochloride. The benzene layer was separated, washed with water, washed with a 5% aqueous sodium bicarbonate solution, washed further with water three times, and dried with sodium sulfate. By distilling away the benzene under reduced pressure, 172 g. of a compound having a boiling point of 190-192 C./2 mm. Hg was obtained.

SYNTHESIS 3 Di-n-hexylphenyl phosphate 326 g. (3.2 mols) of water-free n-hexanol, 270 g. (3.4 mols) of water-free pyridine, and 350 ml. of water-free benzene were placed in a 2 liter three-necked flask equipped with an air-tight agitator, a dropping funnel, a thermometer, and a reflux condenser. While stirring, the mixture was cooled to 5 C. and then 316.5 g. 1.5 mols) of dichlorophenyl phosphate (produced by the method described in Synthesis of Organic Compounds, vol. 12, page 95) was added dropwise at temperatures lower than 10 C. Thereafter, the reaction mixture was maintained at the same temperature for 1 hour and at room temperature for 2 hours, and then refluxed for 2 hours. After reducing the temperature of the reaction mixture to room temperature, 400 m1. of water was added to dissolve the pyridine hydrochloride. The benzene layer was separated, washed with water, 'washed then with a 5% aqueous sodium bicarbonate solution, washed further with water twice, and dried by sodium sulfate. By distilling away the benzene under reduced pressure and then distilling the residue immediately, the fractions having boiling points of -205 C./1.5 mm. Hg were collected and distilled again to give 414 g. of the above-mentioned product having a boiling point of 178-182 C./mm. Hg.

The S-pyrazolone couplers shown by the general Formula II to be used in this invention can be produced by well known methods. For instance, a 3-alkyl-5-pyrazolone or a 3-aryl-5-pyrazolone can be produced by condensing an aryl hydrazine and a corresponding ethyl acyl acetoacetate. Also, 3-amino-5-pyrazolone can be produced by the condensation of an aryl hydrazine and ethyl fi-ethoxyfl-iminopropionate acid. By reacting the 3-amino-5-pyrazolone thus obtained with a carboxylic acid chloride, an isocyanate compound or an arylsulfonyl chloride, 3-acylamino-S-pyrazolone, 3-ureido-5-pyrazolone, or 3-sulfonamido-S-pyrazolone can be obtained respectively. Furthermore, by heating the 3-amino-5-pyrazolone and an aniline to cause a diamination reaction, 3-anilino-5-pyrazolone can be obtained.

A bis-S-pyrazolone represented by the general Formula III can be obtained by condensing 2 mols of the 5-pyrazolone obtained above and one mole of an aldehyde. Examples of the production of the 5-pyrazolones used in this invention are described in the specifications of British Pat. Nos. 547,064; 680,488; 843,497; 904,852; 953,454; 953,455; 977,554; 1,018,810; 1,044,778; 1,057,436; 1,066,- 334; 1,069,534; 1,076,544; 1,077,873; 1,077,875; 1,078,- 164; 1,118,745; and 1,142,553; US. Pat. No. 2,618,641; and Belgian Pat. Nos. 679,766 and 697,112.

The following examples describe preferred embodiments of this invention.

EXAMPLE 1 A solution obtained by heating 17 g. of the 5-pyrazolone-type coupler L shown by the above structural formula, 15 ml. of the coupler solvent and 15 ml. of butyl acetate at 70 C., was added to 300 ml. of an aqueous solution containing 25 g. of gelatin and 1.0 g. of sodium dodecylbenzene sulfonate and after stirring the mixture for 30 minutes using a homogenizer, the entire amount of the dispersion obtained was added to 500 g. of a photographic emulsion containing 36.7 g. of silver iodobromide and 45 g. of gelatin. After adding 15 m1. of a 3% acetone solution of triethylene phosphamide as a hardening agent and adjusting the pH of the emulsion to 7.0, the photographic emulsion was applied to a triacetyl cellulose film to a dry thickness of 4.0 10'- cm. In this case, the coating density was 1.11 10 mol/m. with respect to the coupler and 9.00 10- mol/m. with respect to the silver iodobromide.

The light-sensitive film was exposed and processed as follows, whereby a magenta image was obtained.

1 7 The compositions of the processing solutions used above were as follows:

Color Developer I (pH 10.5):

Water ml 1000 2-amino 5 diethylamino toluene hydrochloride g 2.5 Anhydrous sodium sulfite g 5 Sodium carbonate monohydrate g 47 Potassium bromide g 2 Fixing solution (pH 4.5):

Water mi 1000 Sodium thiosulfate hexahydrate g 80 Anhydrous sodium sulfite g 5 Borax g 6 Glacial acetic acid ml 4 Potassium alum g 7 Bleaching solution (pH 7.2):

Water ml 1000 Potassium ferricyanide g 17 Borax g 5 Boric acid g 10 Potassium bromide g 7 As the solvent for coupler were used diethyldodecyl phosphate [solvent (a) di-n-butyl-(Z-ethylhexyD-phosphate [solvent (d)], and di-(2-ethylhexyl)-n-butyl phosphate [solvent Di-n-butyl phthalate (DBP) and trio-cresyl phosphate (TCP) were used for comparison purposes as conventionally known coupler solvents.

The spectral absorption curves of the magenta images obtained are shown in FIG. 1 of the accompanying drawings and the values of the characteristics thereof are shown in Table 3. In FIG. 1, Curve I represents the spectral absorption curve when coupler solvent (j) was used, Curve II represents the spectral absorption curve when DBP was used, and Curve III represents the spectral absorption curve when T CP was used.

From these results it is clear that when the novel coupler solvent of this invention was used, unnecessary absorption in the wave length region longer than about 600 millimicrons was less and the reproduction of a brighter red color was possible in comparison with the case of using conventionally known coupler solvents. I

These films demonstrated good coupling and gave optical densities of from 2.8 to 3.0 to green light.

TABLE 3 [Relation between solvent and spectral absorption characteristics of the color image obtained] A solution prepared by heating a mixture of 31.4 g. of the 5-pyrazolone-type coupler Q shown by the abovedescribed general formula, 63 ml. of the solvent for the coupler, and 50 ml. of ethyl acetate were added to 700 ml. of an aqueous solution containing 45 g. of gelatin and 3.0 g. of sodium dodecyl sulfate with stirring and they were mechanically stirred vigorously for 30 minutes in a high speed agitator, whereby the coupler was finely dispersed together with the solvent.

The entire amount of the emulsified dispersion was added to 1 kg. of a green-sensitive photographic emulsion containing 2.69 l0- mol of silver iodobromide and 70 g. of gelatin, and after adding additionally 50 ml. of a 3% acetone solution of triethylene phosphamide as a hardening agent, the resulting emulsion was applied to a polyethylene terephthalate film at a dry thickness of 5.5

18 microns. The light-sensitive film contained the coupler in an area density of l.27 10- mol/m The light-sensitive film was subjected to sensitometric exposures and then processed as in Example 1 except that the color developer had the following composition:

Color Developer II:

The spectral absorption curve of the magenta image thus obtained is shown in FIG. 2 of the accompanying drawings and the values of the characteristics thereof are shown in Table 4. In FIG. 2, Curve IV represents the spectral absorption curve where coupler solvent (f) (trin-hexyl-phosphate) was used and Curve V represents the spectral absorption curve where tri-o-cresyl phosphate was used as the coupler solvent.

From these results, it is clear that the coupler solvent of this invention gave a color image having less unnecessary absorption at wavelengths longer than 600 millimicrons. Therefore, a brighter red color reproduction in a color photograph, in comparison with the case of known wupler solvent, was obtained.

The light-sensitive films prepared above showed good coupling on color development. Also, in the light-sensitive films of this invention, the turbidity by the coupler dispersed in the unexposed area thereof was particularly low and the unexposed portions were transparent. Furthermore, the magenta images obtained by the coupling of the coupler demonstrated high resistance to light, heat and humidity in the light-sensitive films of this invention. These results are shown in the following table.

TABLE 5 [Relation between coupler solvent and color image absorption] Fading percentage oi! color image (percent) Solvent (A) (B) (D) Solvent (0) 2. 93 0. 018 25 5 Solvent (i) 3. 05 0. 015 23 4 Solvent (1) 2. 95 0. 015 20 5 Solvent (m) 2. 89 0. 020 20 5 DBP (known). 2. 89 0. 025 35 7 TCP (known)--- 2. 92 0. 030 25 10 Nora-The column headings (A) (D) are as follows: (A)Maximum coupling density; (B)Turbidity of unexposed portions (relative value) (700 m (C)Fade bylight (xenon are, 40 hrs.) (D)Fade by humidity (75% RH, 60 C. 20 days).

EXAMPLE 3 A solution prepared by heating a mixture of 7.3 g. of the S-pyrazolone-type coupler T shown by the above-described general formula, 10 ml. of the coupler solvent, 1 g. of sodium di-isooctyl sulfosuccinate, and 20 ml. of ethyl acetate was added to m1. of an aqueous solution containing 10 g. of gelatin, and the mixture was mechanically stirred for 15 minutes vigorously using a homogenizer, thereby the coupler and the solvent were finely dispersed. The dispersion was stored for 30 days at 5 C.

The entire amount of the dispersion was heated to 50 C. and mixed with 500 g. of a photographic emulsion containing 1.03 x mol of silver chlorobromide and 35 g. of gelatin. After adding additionally 20 ml. of a 3% acetone solution of triethylene phosphamide as a hardening agent, the resultant emulsion was filtered using a glass filter and applied to a triacetyl cellulose film at a dry thickness of 5.5 microns.

The glass filter was washed with warm water thoroughly, dried and weighed and the weight of the filtered residue was measured. The results obtained are shown in column 2 of Table '6.

TABLE 6 [Stability of dispersion and spectral absorption characteristics of the color image] Absorption to red Absorption light maximum u) Residue Solvent Soivent (c) Solvent (h) DBP (known) TOP (known)- 125 Coupler (i) The color photographic light-sensitive films of this invention, in which the coupler solvents (a) and (0) were used, gave clear magenta images having good transmittance to red light, whereas in the comparison sample, in which TBP was used as the coupler solvent, the absorption maximum was at much longer wave length and the absorption to red light was larger. Also, in the latter case, the transmittance of the unexposed portions was low. It is believed that in the latter sample the TBP was dissolved in the processing solution during development and hence the remaining coupler and the dye formed therefrom crystallized in the emulsion layer due to the loss of the solvent.

From these results, it is apparent that the preferable properties required as the coupler solvent are obtained by using the compound belonging to those represented by the general Formula I and having more than 14 carbon atoms.

EXAMPLE 5 A color photographic printing paper was prepared in the following manner.

To a photographic baryta-coated paper was applied as the first layer a blue-sensitive photographic emulsion containing the yellow-forming coupler (i) having the following structure at a dry thickness of 5 microns:

r nU) (53115 H2N COCHzO ONE-- The spectral absorption characteristics of these samples are shown in columns 3-5 of Table 6 above EXAMPLE 4 A solution obtained by heating 15.7 g. of the 5-pyrazolone-type coupler H shown above, 30 ml. of the coupler solvent, and 20 ml. of ethyl acetate was added to 300 ml. of an aqeuous solution of 25 g. of gelatin and 1.0 g. of sodium dodecylbenzene sulfonate and the mixture was vigorously stirred for 30 minutes using a homogenizer to give a dispersion. The entire amount of the dispersion was added to 500 g. of a photographic emulsion containing 36.7 g. of silver iodobromide and g. of gelatin and after adding 15 ml. of a 3% acetone solution of triethylene phosphamide as a hardening agent and adjusting the pH to 7.0, the resultant mixture was applied to a triacetyl cellulose film at a dry thickness of 5 .0x 10- cm.

In Sample 1, Sample 2, and Sample 3, tri-n-butyl phosphate (TBP), diethyl-decyl phosphate, and tri-n-amyl phosphate were used respectively.

When these samples were exposed to an atmosphere of C. and 75% relative humidity for 10 days, the film base was softened and the mechanical strength was reduced in Sample 1, whereas no softening of film base was observed in Sample 2 and Sample 3. Furthermore, it was confirmed that in Sample 1 the coupler solvent, tri-n-butyl phosphate, migrated from the emulsion layer to the film base excessively plasticizing the triacetyl cellulose.

These 3 samples were exposed and processed as in Example 1, whereby magenta color images having the characteristics shown in Table 7 were obtained.

5 and to the blue-sensitive emulsion layer thus formed was applied as the second layer a gelatin solution at a thickness of 1 micron.

A solution produced by heating 16 g. of the 5-pyrazolone-type magenta-forming coupler N shown in the above-described structural formula, 30 ml. of the coupler solvent (f), and 25 ml. of ethyl acetate was added to 300 ml. of an aqueous solution containing 25 g. of gelatin and 1.0 g. of sodium dodecylbenzene sulfonate, and the mixture was stirred for 30 minutes using a homogenizer to give a dispersion. The entire amount of the emulsified dispersion was added to 500 g. of a green-sensitive photographic emulsion containing 36.7 g. of silver bromide and 45 g. of gelatin and after adding 30 ml. of a 3% solution of triethylene sulfamide as a hardening agent and adjusting the pH to 7.0, the resultant mixture was applied to the second layer as the third layer at a dry thickness of 3.5 microns. In this case the density of the magenta coupler in the layer was 8.6x10- moi/m To the green-sensitive layer was applied as the fourth layer a gelatin solution at a dry thickness of 1 micron and then to the gelatin layer was applied as the fifth layer a red-sensitive emulsion containing the cyan-forming coupler (ii) having the following structure:

Cyan-Forming Coupler (ii):

I s M 21 Further, to the red-sensitive layer was applied as the sixth layer a gelatin solution containing a mixture of the ultraviolet absorbers (iii), (iv) and (v) having the structures shown below:

When the color photographic printing paper was exposed to green light and developed as in Example 2, a clear magenta image having an absorption maximum at 536 millimicrons and showing a maximum green density of 2.7 was obtained.

When the printing paper was exposed through a color negative original and developed using the same procedures as in Example 2, a color print having clear color image was obtained. In particular, the bright red reproduction was excellent in the color print.

EXAMPLE 6 A color positive film was prepared in the following manner.

To a triacetyl cellulose film was applied as the first layer a blue-sensitive photographic emulsion containing the yellow-forming coupler (vi) having the following structure at a dry thickness of 6 microns:

Yellow-Forming Coupler (vi) 2 (0 2H5) 2N 0 as 22 robromide and 75 g. of gelatin and after adding ml. of a 3% acetone solution of triethylene phosphamide as a hardening agent, the resultant mixture was applied to the fourth layer at a dry thickness of microns. In this case the density of the magenta coupler was 1.83 millimol/mfi".

Further, to the green-sensitive layer was applied as the uppermost layer a protective layer composed of gelatin at a thickness of 1 micron.

When the light-sensitive film was exposed to green light and processed using the same procedure as in Example 1, a clear magenta image having an absorption maximum at 550 millimicrons and showing the highest green density of higher than 4 was obtained.

The color photographic positive film thus produced was exposed through a color negative and developed as in Example 1 to obtain a color slide for projection having clear colors. When the color slide was projected, it was confirmed that the reddish color was especially clear.

EXAMPLE 7 A color negative film was prepared in the following manner.

To a triacetyl cellulose film having an antihalation layer on the reverse side was applied as the first layer a redsensitive photographic emulsion containing the cyanforming coupler (ii) shown by the above-described structure to a thickness of 1 micron.

A coupler solution obtained by heating a mixture of 12 g. of the 5-pyrazolone coupler H shown by the abovementioned structural formula, 4 g. of the 4-azo-5-pyrazolone coupler U colored yellow, 10 ml. of the coupler solvent (c) and 20 ml. of butyl acetate was mixed with a solution containing 1.5 g. of sodium di-nonylnaphthalene sulfonate and 20 g. of gelatin and the mixture was mechanically stirred vigorously in a homogenizer to disperse the coupler finely.

The entire amount of the dispersion thus prepared was added to 1.6 kg. of a green-sensitive photographic emulsion containing 2.8 10-' mol of silver iodobromide and 97 g. of gelatin. After adding thereto 30 ml. of a 3% acetone solution of triethylene phosphamide as a hardening agent, the resultant emulsion was applied as the third layer to the above-formed layer at a dry thickness of 4 microns.

To the green-sensitive layer were further applied a gelatin solution containing a yellow silver colloid as the fourth layer, a blue-sensitive photographic emulsion containing the yellow-forming coupler (vi) shown above t me OoHO-Q-Qmim @mrooomo oNH--o CH; $51111) To the blue-sensitive layer was applied a gelatin layer of 1 micron. Furthermore, to the layer was applied as the third layer a red-sensitive photographic emulsion containing the cyan-forming coupler (ii) shown above at a dry thickness of 4 microns and to the red-sensitive layer was applied a gelatin layer of 1 micron in thickness as the fourth layer.

A solution obtained by heating a mixture of 28.0 g. of the S-pyrazolone-type coupler L shown by the abovedescribed structural formula, 6.0 ml. of the coupler solvent (d) and ml. of ethyl acetate was added to 350 ml. of a gelatin solution containing 3.5 g. of gelatin and 3.0 g. of sodium dodecylsulfate with stirring and the mixture was mechanically stirred for 30 minutes vigorously using a homogenizer.

The entire amount of the emulsified dispersion thus produced was added to 1 kg. of a green-sensitive photographic emulsion containing 2.8 10" mol of silver chlol0 g. of each of the various magenta couplers shown by the above described structures was dissolved by heating in a mixture of 25 ml. of ethyl acetate and 18 ml. of eachof the various coupler solvents shown by the abovedescribed structures. Each of the coupler solutions prepared above was mixed with 200 ml. of an aqueous solution containing 15 g. of gelatin and 1.0 g. of sodium dodecylbenzene sulfonate and the mixture was mechanically stirred vigorously for 30 minutes using a high speed rotary mixer to disperse finely the coupler and the solvent.

The entire amount of each coupler dispersion was added to 300 g. of a silver halide photographic emulsion and after adding thereto 10 ml. of a 3% acetone solution of triethylenephosphamide as a hardening agent, the resultant emulsion was applied to a triacetyl cellulose film at a dry thickness of microns.

The light-sensitive film thus obtained was developed in the same manner as in Example 2 and the spectral absorption of the magenta image obtained was measured, the results of which are shown in Table 8.

2.6 g. of the coupler F shown by the above-described structure was dissolved by heating in an aqueous medium consisting of 6 ml. of a 1 N solution of sodium hydroxide, 15 ml. of methanol, and 40 ml. of water.

5 ml. of tri-n-amyl phosphate [coupler solvent (c)] was added to 25 ml. of aqueous solution containing 0.1 g. of sodium dodecylbenzene sulfonate and 2.0 g. of gelatin and the mixture was stirred vigorously in a homogenizer to give a dispersion. The entire amount of the dispersion was added to 100 g. of a photographic emulsion containing 269x" mol of silver iodobromide and 7.0 g. of gelatin.

The aboveprepared coupler solution was added to the photographic emulsion obtained above with stirring and then the pH was adjusted to 6.0 with a 6% acetic acid solution. Then, after adding 3 ml. of a 3% acetone solution a triethylene phosphamide thereto as a hardening agent, the resultant emulsion was applied to a triacetyl cellulose film at a dry thickness of 5 microns.

As a control sample, a light-sensitive film was prepared in the same manner as above except that tri-namyl phosphate and sodium dodecylbenzene sulfonate were not used.

By subjecting these light-sensitive films to the developing procedure as in Example 1, magenta images having the following absorption characteristics were obtained.

TABLE 9 [Property of Magenta Coupler] Absorption Red absorp- Solvent for maximum tion ratio Sample coupler (m D600/Dmx.

Invention-.. Solvent (b) 545 0.340 Control None 556 0.431

EXAMPLE 10 A mixture of 16 g. of the S-pyrazolone coupler M shown by the above described structure, 24 ml. of the coupler solvent (h), and 25 ml. of butyl acetate was heated to give a coupler solution.

A solution produced by heating a mixture of 2 g. of l-(3'-sulfo-4-phenoxy)-3-stearyl-5-pyrazolone, 3 m1. of a. 1 N solution of sodium hydroxide, and 50 ml. of water was added to 1 kg. of a green-sensitive photographic emulsion containing 0.21 mol of silver chloride and 70 g. of gelatin. The emulsion was heated to 40 C. and mixed with the hot solution of the coupler M prepared as above followed by stirring. Then, the mixture was passed five times through an emulsifier having Pohlman Whistle, whereby the coupler was dispersed finely.

The photographic emulsion was applied to a triacetyl cellulose film at a dry thickness of 5 microns.

The light-sensitive film thus obtained was exposed and developed as in Example 2, whereby a clear magenta image having an absorption maximum at 538 millimicrons was obtained.

EXAMPLE l1 5 ml. of tri-(Z-ethylhexyl) phosphate [coupler solvent (m)] was added to 70 ml. of an aqueous solution containing 5 g. of gelatin and 0.3 g. of sodium cetylsulfate and the mixture was stirred vigorously in a small emulsifying blender to disperse the solvent finely.

The entire amount of the dispersion was added together with 50 ml. of warm water to g. of a photographic emulsion containing 0.27 mol of silver iodobromide and 7 g. of gelatin, and the mixture was mixed with 18 ml. of a 6% acetic acid solution.

2.37 g. of the S-pyrazolone coupler Z shown by the above-described structural formula was added to a mixture of 5 ml. of methanol, 15 ml. of 1 N solution of sodiumv hydroxide, and 30 ml. of water, and heated to form the solution. The coupler solution was added to the photographic emulsion prepared above with thorough stirring. After adjusting the pH of the mixture with a 1 N solution of sodium hydroxide and adding a 3% acetone solution of triethylene phosphamide as a hardening agent, the resultant emulsion was applied to a triacetyl cellulose film at a thickness of 6 microns.

For comparison purposes, the same c'oupler was added to the photographic emulsion using an aqueous solution system without using the coupler solvent and sodium cetylsulfate to prepare a control film sample.

When these light-sensitive films were exposed and developed as in Example 2, magenta images having the properties shown in the following table were obtained.

In the same manner as above, six types of film samples were prepared using 2.9 g. of the S-pyrazolone-type coupler '(A'), 3.3 g. of the 5-pyrazolone-type coupler (B), and 3.05 g. of the S-pyrazolone-type coupler (C') respectively, each shown by the above-described structural formulae. These light-sensitive films were also exposed and developed, the results are shown in the following table.

As is clear fiom the above table, the absorption of the color image formed from the photographic emulsion containing the tri-(Z-ethylhexyl) phosphate shifted to shorter wave lengths and had less unnecessary absorption of red light. Furthermore, by the addition of the coupler solvent the shape of the spectral absorption curve of the color image was sharpened, which contributed to a reduction in the absorption in the blue region and the red region.

EXAMPLE 112 1 6 g. of the S-pyrazolone coupler M shown by the aforesaid structural formula was dissolved in 40 ml. of butyl acetate by heating. The solution was added to an aqueous solution containing 11 g. of gelatin and 1 g. of sodium di-isooctylsulfosuccinate at 50 C. and stirred for 15 minutes in a homogenizer to disperse the coupler finely.

24 ml. of di-n-hexyl-phenyl phosphate [coupler solvent (h)] was added at 50 C. to an aqueous solution containing 6 g. of gelatin and 0.6 g. of sodium di-isooctylsulfosuccinate and the mixture was stirred for 15 minutes in a homogenizer to disperse [finely the solvent for the coupler.

. The coupler dispersion and the coupler solvent dispersion prepared above were added to 1 kg. of a greensensitive photographic emulsion containing 0.21 mol of silver chlorobromide and 70 g. of gelatin and after adding thereto 30 ml. of a 3% acetone solution of triethylene phosphamide as a hardening agent, the emulsion was applied ot a polyethylene terephthalate film at a dry thickness of 5 microns.

For comparison purposes, a control sample was prepared by adding only the coupler dispersion to the photographic emulsion without adding the coupler solvent dispersion.

These film samples were exposed and developed as in Example 1. The spectral absorption curves of these color images are shown in FIG. 3 of the accompanying drawings. In FIG. 3, curve VI represents the spectral absorption curve when the coupler solvent (h) was used, while curve VII represents the case in which no such coupler solvent was used.

As is clear from these absorption curves, the coupler solvent contributed to the shift in the absorption to shorter wave lengths side and to the reduction in the absorption in the red region.

What is claimed is:

1. A light-sensitive material comprising at least a layer of a silver halide emulsion containing (1) a non-diffusing S-pyrazolone coupler having at least a hydrophobic ballasting group containing from -9 to 30 carbon atoms and (2) a coupler solvent having the formula wherein R and R each is an alkyl group and wherein R represents a member selected from a group consisting of an alkyl group and an aryl group, and wherein the total number of the carbon atoms in R R and R ranges from :14 to 40 carbon atoms.

2. A light-sensitive material as claimed in claim 1, wherein said S-pyrazolone coupler is a member selected from the group consisting of compounds having the following formulae:

wherein R is a member selected from a group consisting of aryl and substituted aryl, said substituted aryl having a group member selected from the group consisting of aryl, alkoxyl, aryloxy, alkylthio, arylthio, halogen, tritluoromethyl, cyano, acyl, sulfonyl, acylamino, sulfonamino, ureido, amino, carboxyl, al koxycarbonyl, and carbamyl, wherein R is a member selected from a group consisting of alkyl, alkenyl, aryl, amino, acylamino, ureido, alkoxyl and sulfonamino, wherein R is a member selected from a group consisting of a lower alkyl and a lower aryl group, wherein X represents a substituent displaceable on the reaction with the oxidation product of a primary aromatic amino developing agent and is selected from the group consisting of a hydrogen atom, an arylazo, an aryloxy and an arylthio group, and wherein at least one of R and R contains a hydrophobic ballasting group containing from 9 to 30 carbon atoms.

3. A light-sensitive material as claimed in claim 2, wherein said coupler is a l-(substituted aryl)-3-acylamino- S-pyrazolone.

4. A light-sensitive material as claimed in claim 2, wherein said coupler is a l-(substitnuted aryl)-3-ureido S-pyrazolone.

5. A light-sensitive material as claimed in claim 2, wherein said coupler is a l-(substituted aryl)-3-anilino- S-pyrazolone.

6. A light-sensitive material as claimed in claim 1, wherein the weight ratio of said coupler solvent to said coupler ranges from 0: 1:1 to 4:1.

7. A light-sensitive material as claimed in claim 1, wherein said coupler solvent is a member selected from the group consisting of diethyl decyl phosphate, tri-n-amyl phosphate, di-n-butyl 2-ethylhexyl phosphate, tri-n-hexyl phosphate, di-n-hexyl phenyl phosphate, tris-(Z-ethylhexyl) phosphate, di-(2-ethylhexyl) n-butyl phosphate.

8. A light-sensitive material as claimed in claim 1, wherein R R and R each is a primary alkyl group.

9. A light-sensitive material as claimed in claim 1, wherein R and R each is a primary alkyl group and wherein R is a mono-nuclear aryl group.

10. A light-sensitive material as claimed in claim 1, wherein said hydrophobic ballasting group is contained in a substituent at the 3 position of the S-pyrazolone nucleus.

11. A process for producing a colored image by reacting a non-diffusing S-pyrazolone coupler with the oxidation product of a primary aromatic amino developing agent oxidized by exposed silver halide, in the presence of a coupler solvent having the formula I Ra wherein R and R each is an alkyl group and wherein R represents a member selected from the group consisting of an alkyl and an aryl group, and wherein the total number of carbon atoms in R R and R ranges from 14 to 40 carbon atoms.

12. The process as claimed in claim 11, wherein said S-pyrazolone coupler is a member selected from the group consisting of compounds having the following formulae wherein R is a member selected from a group consisting of aryl and substituted aryl, said substituted aryl having a group member selected from the group consisting of aryl, alko/xyl, aryloxy, alkylthio, arylthio, halogen, trifluoromethyl, cyano, acyl, sulfonyl, acylamino, sulfonamino, ureido, amino, carboxyl, al'koxycarbonyl, and carbamyl, wherein R is a member selected from the group consisting of alkyl, alkenyl, aryl, amino, acylamino, ureido, alkoxyl and sulfonamino, wherein R is a member selected from a group consisting of a lower alkyl and a lower aryl group, wherein X represents a substituent displaceable on the reaction with the oxidation product of a primary aromatic amino developing agent and is selected from the group consisting of a hydrogen atom, an arylazo, an aryloxy and an arylthio group, and wherein at least one of R and R contains a hydrophobic ballasting group containing from 9 to 30 carbon atoms.

13. The process as claimed in claim 12, wherein said coupler is a l-(substituted aryl)-3-acylamino-5-pyrazolone.

14. The process as claimed in claim 12, wherein said coupler is a l-(substituted aryl)-3-ureido-5-pyrazolone.

15. The process as claimed in claim 12, wherein said coupler is a l-(substituted aryl)-3-anilino-5-pyrazolone.

16. The process as claimed in claim 12, wherein the weight ratio of said coupler solvent to said coupler ranges from 0.1:1 to 4:1.

17. The process as claimed in claim 11, wherein said coupler solvent is a member selected from the group consisting of diethyl decyl phosphate, tri-n-amyl phosphate, di-n-butyl 2-ethylhexyl phosphate, tri-n-hexyl phosphate, di-n-hexyl phenyl phosphate, tri-(Z-ethylhexyl) phosphate, di (2-ethylhexyl) n-butyl phosphate, and tri-n-heptyl phosphate.

18. The process as claimed in claim 11, wherein R R and R each is a primary alkyl group.

19. The process as claimed in claim 11, wherein R and R each is a primary alkyl group and wherein R is a mono-nuclear aryl group.

20. The process as claimed in claim 11, wherein said hydrophobic ballasting group is contained in a substituent at the 3 position of the 5-pyrazolone nucleus.

References Cited UNITED STATES PATENTS 2,801,171 7/1957 Fierke et a1 96--100 2,949,360 8/1960 Julian 96100 3,057,721 10/1962 Cowden et a1. 96100 J. TRAVIS BROWN, Primary Examiner US. Cl. X.R. 9622, 74, 84, 100 

